Preventing adolescents' uptake of smoking.

Smoking is the principal preventable cause of ill health worldwide. It not only affects smokers themselves but is also extremely harmful to non-smokers who inhale environmental tobacco smoke (ETS). In non-smoking adults, ETS exposure causes lung and other cancers, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, asthma and other respiratory illnesses. Perhaps less well known by the general public is the threat that ETS inhalation poses for infants and children; there are strong associations with children’s asthma, lower respiratory tract infection, sudden infant death syndrome, middle ear infection and bacterial meningitis. 4 Knowledge of the health risks of ETS exposure have led many countries, including the UK, to introduce laws that prohibit smoking in indoor public spaces like bars and pubs (smoke-free legislation). Advocates of smoke-free laws successfully argued for these on the basis of protecting nonsmokers who might work in or visit smoky environments. Consequently, as tobacco smoke has been completely eliminated from most situations in which adult non-smokers might encounter it, they are well protected from ETS. No similar protection exists for the children of smokers. Most of children’s exposure to tobacco smoke occurs domestically 4 but, internationally, there are no smoke-free laws which forbid smokers from ‘lighting up’ in their homes when children are present. Children’s domestic ETS exposure therefore remains an important public health concern which, as Leonardi-Bee and colleagues show in Thorax, is even more harmful than was previously thought. The authors show that children’s exposure to ETS from parental smoking has a pervasive inter-generational behaviourmodelling effect such that the children of smokers are much more likely to become smokers themselves. Their systematic review and meta-analysis collated findings from 58 epidemiological studies investigating associations between parental smoking and the subsequent development of established smoking in offspring. When both parents smoke, the risk of their children becoming smokers almost triples; if only one parent or a sibling smokes the risk is lower but, even then, children are between 1.75 times and twice as likely to become smokers than those not exposed to parents’ or siblings’ smoking. The consistency of findings from individual studies comprising the review is striking; virtually all component studies reported a positive association between parental/ sibling smoking and children’s subsequent uptake of the habit, lending strong support to the authors’ conclusion that associations are probably causal. Of course, smoking is strongly associated with household psychosocial problems 8 and it is possible that, for some young people, these issues have more of an impact on their future smoking behaviour than parental smoking itself. Nevertheless, it seems very unlikely that the normalising impact of persistent parental smoking within the home would have no effect. Parental smoking in the home therefore has direct, substantial and immediate impacts on children’s health from inhaled ETS and also, in those children who become adult smokers as a consequence of learned smoking behaviour, it has serious longer-term indirect effects mediated by their future smoking. Leonardi-Bee and colleagues call for ‘radical changes in public policy and behaviour and in the acceptability of smoking in places where children are present’. However, while arguments for eliminating smoking in the presence of children are compelling, quite how this could be achieved remains unclear. Legislative changes that curtail widespread behaviours need both robust public support (to ensure that new laws are obeyed) and effective compliance mechanisms (to ensure that breaking new laws has a reasonable chance of incurring penalties). There was strong public support for smoke-free laws before these were introduced in the UK and public support increased after the introduction of the legislation, even among smokers. Observance of the smoke-free laws was rigorously enforced by local authority environmental health departments. These factors probably explain why in Scotland smoke-free legislation has been thoroughly implemented with high compliance, and in England it is now highly unusual to inhale other people’s tobacco smoke in indoor public spaces. Not all public health-orientated legislation is adhered to as comprehensivelydfor example, using a mobile telephone while driving is also illegal in the UK but car drivers are often seen talking on their telephones. A radical change in public health policy might be to ban smoking in public outdoor places where children are present (eg, children’s play areas or in all school grounds). Such a law has recently been introduced in Spain and its impacts need evaluating. However, many Spanish smokers will still probably smoke in the home, ‘teaching’ their children to smoke and exposing them to ETS. Indeed, it is difficult to envisage how public healthorientated legislative changes could influence parents’ smoking behaviour to such an extent that their children would never see them smoking. Laws banning smoking in homes where children live would be unlikely to have much effect; many smokers at whom such laws would be targeted would probably oppose them and there would be no clear mechanism for enforcing compliance. If people choose to ignore the law and smoke in their homes, how and by whom would this be detected? For law breakers, would there be any significant risk of sanction? If legislation is unlikely to stop children from seeing their parents smoke or inhaling ETS from their cigarettes, then what other measures could achieve this? Ideally, any smokers who become parents would immediately stop smoking, transforming themselves into positive health role models for their children. Some parents do manage this but many do notdillustrated, for example, by the very high rates of relapse to smoking after childbirth observed among women who managed to stop smoking while pregnant. It is therefore clear that a proportion of parents will continue to smoke in their homes when children are present; finding and implementing strategies for minimising the impacts of this destructive Division of Primary Care, UK Centre for Tobacco Control Studies, University of Nottingham Medical School, Queen’s Medical Centre, Nottingham, UK; Stirling Management School, UK Centre for Tobacco Control Studies, University of Stirling, Stirling, UK